Generally, a conventional transconductor for processing audio signals uses Switched-Capacitor of the characteristics of voltage controlled voltage source ("VCVS") to acquire high precision performance. However, in order to process mobile communication signals or VHF image signals, an operational amplifier having a wide bandwidth is needed so that the area of the integrated circuit is increased for this large operational amplifier.
As one of the conventional solutions to the above mentioned problem, a transconductance which uses a voltage controlled current source ("VCCS") is suggested. FIG. 1 shows a circuit diagram of the conventional VCCS transconductor.
However, the overall dynamic range of the conventional transconductor is narrow because the operating point of input terminals of the transconductor is unstable. Further, since the output resistance of the transconductor is small, when this transconductor is used in, for example, a filter, the characteristics of the filter is degraded. Still further, the transconductance of the conventional transconductor can not be adjusted by users.